For the period of about a month, whenever I would try to log on, I would get a message saying I was banned from the forum for use of more than one account. It also said the ban was not set to expire. Why'd I get banned? I've never done anything bad on here before.

I've looked at your account. I don't see any ban or suspension associated with your account, and I don't see any bans associated with any of the IP addresses you've previously logged in from. Without additional information, I can't track down the specific issue but it appears you're able to access the website now.